Micellar electrokinetic chromatograph

A Fuertoes-Matei, J Li, KC Waldron. Micellar electrokinetic chromatographic study of interaction between enkephalin peptide analogs and charged micelles. J Chromatogr B 695 39-47, 1997. 

As a nanotechnology, HP-CZE, as well as the micellar electrokinetic chromatographic extension (HP-MEKC) of the technique, provide important avenues for the rapid analysis of peptides. As such, the techniques offer valuable orthogonal capabilities to the RPC procedures, which form the mainstay of peptide separation and purification. 

A micellar electrokinetic chromatographic method allows the separation of optically isomeric diltiazem hydrochloride using bile salts as chiral surfactants. The chiral separation of diltiazem hydrochloride from several analogs is achieved at ambient temperature using 0.05M sodium taurodeoxycholate in a 0.02M aqueous phosphate-borate buffer solution of pH 7.0. Separation is performed using a fused-silica capillary tube (650 mm x 50 mm I.D.) and a voltage up to +25 kV. Detection is achieved on-column using UV adsorption at 210 nm (31). 

Separation of kavalactones was also achieved by supercritical fluid chromatography using methanol-modified carbon dioxide as the mobile phase. An optimal separation was achieved on either an amino or protein C4 column at 125 atm and 80 °C. Semipreparative separation of kavalactones was also obtained with two columns connected in series (Ashraf-Khorassani etal., 1999). A micellar electrokinetic chromatographic method with diode-array detection has also been developed for the identification and quantitative determination of the major kavalactones from extracts of P. methysticum... 

Sakudinskaya, I. K., Desirodero, C., Nardi, A., and Fanali, S. Micellar electrokinetic chromatographic study of hydroquinone and some of its ethers. Determination of hydroquinone in skin toning cream, J. Chromatogr., 596, 95, 1992. 

Hillaert S., De Beer T.R., De Beer J.O., Van den Bossche W., Optimisation and validation of a micellar electrokinetic chromatographic method for the analysis of several angiotensin-II-receptor antagonists. J. Chromatogr. A, 984, 135-146 (2003). 

Wakida, S-I. et al. On-chip micellar electrokinetic chromatographic separation of phenolic chemicals in waters. J. Chromatogr. A 1109, 179, 2006. 

Bishop, S. C., et al. "Micellar Electrokinetic Chromatographic Screening Method for Common Sexual Assault Drugs Administered in Beverages." Forensic Science International, 141 2004, 7-15. 

Recently a new method was developed for the complete liquid chromatographic separation and diode array detection of standard mixtures of the 14 most frequently used synthetic colorants. Protocols for RP-HPLC - " and IP-HPLC techniques have been extensively described and the techniques were compared with micellar electrokinetic capillary chromatography, - which has been shown to be suitable for the analysis of synthetic colorants. 

Hu S, Li PCH (2000) Micellar electrokinetic capillary chromatographic separation and fluorescent detection of amino acids derivatized with 4-fluoro-7-nitro-2,l,3-benzoxadiazole. J Chromatogr A 876 183-191... 

Lee et al. [30] described a micellar electrokinetic capillary chromatographic method for the determination of some antiepileptics including valproic acid. They used a fused silica capillary column (72 cm x 50 pm) and SDS as the micellar phase and multiwavelength UV detection. Reaction conditions, such as pH and concentration of running buffer were optimized. Solutes were identified by characterizing the sample peak in terms of retention time and absorption spectra. Recoveries were 93-105%. 

Micellar electrokinetic capillary chromatography with photodiode array detection was used for the determination of polyaromatic hydrocarbons in soil [65]. A detection limit of lOpg and linear calibration over five orders were observed. Compared to a standard gas chromatographic analysis method, the miscellar electrokinetic chromatographic method is faster, has a higher mass sensitivity and requires smaller sample sizes. 

Micellar electrokinetic chromatography (MEKC) and capillary electroki-netic chromatography (CEC) are, as their names imply, chromatographic techniques... 

Excellent chromatographic performance using micellar electrokinetic chromatography (MEKC) has been demonstrated for the a-, / -, and iso-a-acids. Thus the six major components of a mixture of a- and /3-acids can be baseline resolved within 10 minutes (47). Similarly, the six major iso-a-acids can be baseline resolved within 20 minutes (48). De Keukeleire presented MEKC separations of the p- and tetrahydroiso-a-acids that compared well with conventional HPLC analyses (17). 

Enormous advances and growth in the use of ordered media (that is, surfactant normal and reversed micelles, surfactant vesicles, and cyclodextrins) have occurred in the past decade, particularly in their chromatographic applications. New techniques developed in this field include micellar liquid chromatography, micellar-enhanced ultrafiltration, micellar electrokinetic capillary chromatography, and extraction of bioproducts with reversed micelles techniques previously developed include cyclodextrins as stationary and mobile-phase components in chromatography. The symposium upon which this book was based was the first major symposium devoted to this topic and was organized to present the current state of the art in this rapidly expanding field. 

Chromatographic and related electrophoretic methods for the separation of transition metal complexes or their ligands were reviewed . Micellar electrokinetic chromatography (MEKC) presents a new development in the field of capillary zone electrophoresis (CZE). The use of micellar solutions expands the application of CZE to electronically neutral solutes, as well as charged ones. Thus, electrically neutral / -diketonates Cr(dik)3, Co(dik)3, Rd(dik)3, Pt(dik)2 and Pd(dik)2 were separated by CZE in micellar solutions of sds. A linear log-log relationship was found between the distribution coefficient and the partition coefficient of the complex between dodecane and water, which was used for prediction of both the distribution coefficients and the migration times of different metal complexes . 

Micellar Electrokinetic Capillary Chromatography. Surfactants that form micelles in solution are added to the buffer in the capillary. When the solute is injected, it partitions itself between the buffer and the micelle. Migration of the solute depends on the amount of time it spends in the micelle versus the time it spends in the buffer. Therefore, the separation of analytes occurs due to differences in the partition coefficient between the two phases, much like in a chromatographic process. 

Various papers related to the simultaneous determination of creatinine and uric acid can be found in the hterature. Several authors have developed capillary zone electrophoresis (CZE) methods for simultaneous analysis of these compounds in urine. The CE analysis of these renal markers offers some advantages when compared with chromatography, such as shortened separation time, reduced reagent consumption, and increased resolution. Capillar micellar electrokinetic chromatography has been applied to the simultaneous separation of creatinine and uric acid in human plasma and urine. However, chromatographic techniques are widely accepted for the determination of these compounds. Reversed-phase and ion... 

S. Terabe, Micellar electrokinetic chromatography, in Capillary Electrophoresis Technology (N. A. Guzman, ed.). Chromatographic Science Series Vol. 64, Marcel Dekker, Inc., New York, 1993 Chap. 2. 

---